Device comprising a cathode-ray oscillograph adapted to make at least two measuring voltages simultaneously perceptible



April 5, 1949. E. E. CARPENTIER DEVICE COMPRISING A CATHODE-RAYOSCILLOGRAPH ADAPTED TO MAKE AT LEAST TWO MEASURING VOLTAGESSIMULTANEOUSLY PEHCEPTIBLE Filed April 22, 1946 FIG. I

FIG. 2

iNvENToR EDMOND EGBERTUE CARPENT ER ATTQRNEY Patented Apr. 5, 1949UNITED sTATss DEVICE COMPRISING A CATHODE-BJAY OSCILLOGRA'PH ADAPTED TOMAKE AT LEAST TWO MEASURING VOLTAGES SIMULTANEOUSLY PERCEPTELE.

Edmond Egbertus Carpenti er, Eindhoven, Netherlands, assignor, by mes'nelassignments, to Hartford National Bank and Trust Company, Hartford,Conn., as trustee Application April 22, 1946, Serial No. 663,809 In theNetherlands February 9, 1942 Section 1, Public Law 690, August-8, 1946Patent expires February 9, 1962 5 Claims. (Cl. v31!5-26) This inventionrelates to a device adapted to make 'tWO or more non-recurring orrecurring phenomena simultaneously perceptible, measuring voltagescorresponding to these phenomena alternately controlling in rapidsequence the devflection in one and the same direction of thecathode-ray beam of a cathode-ray oscillograph. The measuring voltagesmay then alternately be supplied, for example with the aid of a rotarymechanic switch (cfqfor example British patent 1.-

specification No. 403,060), to a deflection system of the cathode-rayoscillograph, whereas the other deflection system has supplied to it,for example, a time-base voltage which in the case of recurringphenomena varies preferably in synchronism with one of these phenomenaor a harmonic thereof.

For the purpose of alternately supplying the phenomena to theoscillograph, discharge paths serving as inertialessswitches arepreferably used instead of mechanic switches. Diodes or block 'ing-layerrectifiers may" be used, for example,

which are blocked perio'dically'with-the aid of an auxiliary alternatingvoltage of preferably sinusoidal or" rectangular form (of. Britishpatent specification 476,224). It is also possible'toutilise gaseousdischarge tubes as substantially inertialess switches (of. for examplethe article by R. Sewig-in Zeitschrift fiir technische Physik1933-, vol.14, pages 152; 153). grid-controlled high-vacuum tubes may be used asswitching tubes (of. for example the last-mentioned article and alsoFrench patent specifica- -tion 654,354 and British patent specificationThe auxiliary voltage required: when discharge pathsare used asswitches, which voltage'prefer- :ably varies rectangularly with time,may be generated, for example, with the aid of a cathoderay tube inwhich a certain number of collecting electrodes are arranged beside eachother and successively -struck by the cathode-ray beam (of. for examplethe above-mentioned French patent specification No. 654,354), or it maybe derivedfrom a multivibratorcircuit.

The frequency of.switching, he. the frequency of the auxiliary voltage,for non-recurring phenomena is chosen in such manner that it isconsiderably higher :than the fundamental fre- ;quency of thephenomenato @beobserved; in the- Further, the ordinary case of recurringphenomena the frequency of switching, in addition to being considerablyhigher than the fundamental frequency, may be chosen such that itcorresponds td the fundamental frequency or a subharmonic thereof (cf.for example the above-stated British patent specification No. 403,060).In the former case the screen of the cathode-ray tube has formed on. itcurves produced in points, in the latter case not interrupted curves.

The known devices of the indicated type, independently of the switchingdevice or the frequency of switching utilized, have the drawbackoscillogram may be avoided as much as possible.

According to the invention, the said drawback in devices of this kind isobviated by that the times-during which at least two of the measuringvoltages control the deflection of the cathode-ray beam are madedifierent from each other.

For example, when taking a twofold oscillo- =gram, one thus obtains thatthe measuring voltage having the larger amplitude is longer active thanthe other measuring voltage. Since the mean quickness of writing of thecathode-ray beam (i. e. the quickness with which the cathode- .ray beamis moved across the screen) increases with the amplitude of themeasuring voltage to be recorded, as a result of which the lightintensity of the image obtained is smaller according as the amplitude islarger, the effect of the greater quickness of writing'upon the lightintensity is neutralised by causing the measuring voltage having thelarger amplitude to be longer active. It is thus possible with measuringvoltages having'different amplitudes to obtain curves of at leastsubstantially equal light intensity and consequently equal sharpness.

For the purpose of obtaining an optimum adaptation of the times duringwhich the'diiferfigure.

.4. uring voltage A will act'npon the oscillograph during a longer timethan the measuring voltage 1 B, so that with a larger amplitude of themess-- Fig. 2 showsas a function of time the auxiliary voltageused inthe device of Fig. 1 for switching. In Fig. 1, I and 2 are amplifyingtubes serving:

respectively to amplify the measuring voltages,

A and B supplied to the control grids concerned,

the amplified measuring voltages set up at the anode resistance which iscommon to both tubes being suppliedvia a condenser lto'the verticaldeflecting electrodes of a cathode-ray o'scillograph 6. A sawtoothtime-base voltage- 9 is supplied to the horizontal deflectingelectrodes, for example via terminals 8.

The amplifyingtubes l and 2 are alternately released and blocked inrapid sequence by means of a rectangular auxiliary alternating voltagewhich is set upat aresistance Ill interposed-be tween the screen gridsof the amplifying tubes I and 2 and is derived from a multivibrator cir-V cult of a construction :known per se;

For the mutual displacement in thevertical uringvoltage A curves ofequal intensity and sharpness are nevertheless obtained.

As mentioned above, it isadvantageous to regulate the ratio of the timest1 and t2. In the device Shown this y be effected by varyin theresistance H1 in the multivibrator circuit, as 18 schematicallyindicated by an arrow in the It. is evident that the invention may beapplied similarly to-devices for oscillographin'g more than twomeasuring voltages. 'In recording, for ex-" ample, non-recurringelectrical phenomena of ,which the variation of voltage and'current-in acircuit as a function of time, as well as a sinusoidal reference voltagemust be recorded simul- 'taneously, it is frequentlyadvantageous thatthe voltage and the current to be measured are active duringapproximately equally great times, but that the'reference voltage isactive only during a considerably shorter time. age required thereformay be generated, for ex-- ample, with the aid of a. rotary mechanicswitch,

"the extremity of a switching arm moved with direction of the curves A,B produced on the screen of the cathode ray tube, the cathodes of theamplifying tubes are connected to an ad-' justable tapping point of theresistance Hi.

The multivibrator circuit comprises tWopush- 7 null connected andcrosswisefeedback-coupled' screen-grid tubes l2, 13, the feed-back beingeffected 'Withthe aid of. condensers l4, l5 connested between the screengrid of the one tube and the control grid of the other tube.

The control grids of the tubes are connected to the earthed cathodesthrough resistances l6 and [1 respectively, while screen-gridresistances I8, [9 are connected to the positive terminal 22 of a sourceof direct voltage (not shown) through a resistance 2! shunted by acondenser 20.

The output voltage of the multivibrator circuit is derived from theanode resistances 23, 2d and supplied to the resistance ill via.separating condensers 26. The point of connection of the anoderesistances 23, 23 is also connected to the terminal. 22 of the sourceof direct voltage.

In the known devices of the indicated type for producing twofoldoscillograms, the multivibrator circuit is constructed entirelysymmetrically, so that the times during which the amplifying tubes 1 and2 were alternately active and hence also the times during which thedifferent measuring voltages controlled the oscillograph were alwaysequally great.

According to the invention, in the device shown the symmetry of themulti-vibrator circuit is intentionally avoided, for example by givingequal values to the condensers M, I5 but different values to theresistances l6, IT.

The output voltage on of the asymmetric multivibrator circuit thusobtained exhibits, for example, the variation shown in Fig. 2 as afunction of the time t, the time t1 during which the tube i2 istraversed by current and consequently the am lifyin Lulu: l 1:: blocked,bclug considcrably smaller than the time 252 during which the tube I3 istraversed by current and the amplif ing tube- 2 is blocked.Consequently, the mensuniform quickness touching successively threedifferent contact surfaces, two of which are of equal width, whereas thethird contact surface has a considerably smaller width.

.In addition .to' the stated advantage of equal intensity of all thecurves produced, with'the' use I of the inventionone also obtains, forexample, in the last-mentioned case, a more detailed reproduction of theDhen'omen'a to be'meas'ured,

It has been found that in particular when the I multiple oscillogramsobtained, are photographed an appreciable improvement is achieved'by'theuse of the invention. I WhatI claim is:

ll An oscillographic system adaptedtoexhibit simultaneously along acommon time base the waveforms of a plurality of voltages havingdifferent amplitudes, said system comprising a cathode-ray tube having afluorescent screen and first and second deflection means for displacingthe ray in mutually perpendicular directions, means to apply a sawtoothtime base wave of a prescribed frequency and amplitude onto one of saiddeflection means, and means independent of said base wave to applysequentially onto the other of said deflection means each of saidvoltages for a period whose duration depends on the amplitude thereofwhereby the waveforms displayed on said screen are of substantially likeintensity.

2. An oscillographic system adapted to exhibit simultaneously along acommon time base the waveforms of first and second voltages havingdiiferent amplitudes, said system comprising a cathode-ray tube having afluorescent screen and first and second deflection means for displacingthe ray in mutually perpendicular directions, means to apply a sawtoothtime base wave of a prescribed frequency and amplitude onto one of saiddeflection means, means to apply alternately said first and secondvoltages onto the other of said deflection means, and means independentof said base wave to control the time ratio of the periods during whichthe respective voltages are applied onto said other deflection means inaccordance with the ratio of the amplitude of said voltages.

3. An oscillographic system adapted to exhibit simultaneously along a,common time base the waveforms 01' first and second voltages having Theauxiliary voltdifferent amplitudes, said system comprising a cathode-raytube having a fluorescent screen and first and second deflection meansfor displacing the ray in mutually perpendicular directions, means toapply a sawtooth time base wave of a prescribed frequency and amplitudeonto one of said deflection means, a pair of amplifiers each arranged toimpress a respective one of said first and second voltages onto theother of said de flection means, and means independent of said base wavefor alternately rendering said amplifiers operative for a period whoseduration is proportional to the amplitude of the voltage applied as aninput thereto.

4. An oscillographic system adapted to exhibit simultaneously along acommon time base the waveforms of first and second voltages havingdifferent amplitudes, said system comprising a cathode-ray tube having afluorescent screen and first and second deflection means for displacingthe ray in mutually perpendicular directions, means to apply a sawtoothtime base wave of a prescribed frequency and amplitude onto one of saiddeflection means, a pair of amplifiers each arranged to impress arespective one of said first and second voltages onto the other of saiddeflection means, means independent of said base wave for alternatelyrendering said amplifiers operative for a period whose duration isproportional to the amplitude of the voltage applied as an inputthereto, said last named means including an asymmetrical multivibratorproducing alternating rectangular pulses, each of said pulses beingapplied to said first and second amplifiers to disable one andsimultaneously render the other operative.

5. An oscillographic system adapted to exhibit simultaneously along acommon time base the waveforms of first and. second voltages havingdifferent amplitudes, said system comprising a cathode-ray tube having afluorescent screen and first and second deflection means for displacingthe ray in mutually perpendicular directions, means to apply a sawtoothtime base wave of a prescribed frequency and amplitude onto one of saiddeflection means, a pair of amplifiers each including an electrondischarge device having a control grid, a screen grid a d an anode, theanodes of the amplifier devices both being coupled to the other of saiddeflection means, means to apply said first and second voltages to therespective control grids of said amplifier devices, and an asymmetricalmultivibrator independent of said base wave for alternately renderingsaid amplifiers operative, said multivibrator including a pair ofelectron discharge devices each having a control grid, a screen grid andan anode, said pair of devices being arranged in push-pull relation, thescreen grid in each of said pair of devices being feedback coupled tothe control grid in the other, the anodes of said pair of devices beingcoupled respectively to the screen grids of said amplifier devices.

EDMOND EGBERTUS CARPENTIER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date Re. 20,945 Bedell Dec. 13, 19382,221,115 Shepard, Jr Nov. 12, 1940 2,300,999 Williams Nov. 3, 19422,375,709 Thompson May 8, 1945

